Lesions of the anterior and middle skull base are diverse in their etiology and cause significant morbidity due to close proximity to the carotid arteries, brain, orbits, optic nerves and chiasm. For most lesions, a surgical biopsy, excision, or debulking is an essential aspect of treatment. Technological advances over the past few decades now permit transnasal endoscopic surgical access in many instances, which has dramatically reduced the morbidity of gaining surgical access compared to an open craniotomy approach. However, transnasal access is not sufficient for all lesions, which require an open craniotomy if lateral structures are involved. The geometric constraints at the pyriform aperture limit the angle between instruments to 15 degrees when manipulating a target at a depth of 9 cm on the skull base. To improve the ability to manipulate a target, one option is to widen the angle between instruments by using additional surgical portals. Many portals are described to access the skull base, but little work has been done on combining different portals in order to optimize an approach for a certain target location; portals include transnasal, transoral, transorbital, supraorbital, transmaxillary, transcervical, and transventricular. A multidisciplinay team of engineers and surgeons from subspecialties including otolaryngology, neurosurgery, urology and robotic surgery, and orbital surgery has been assembled. Within the team are professors, attending surgeons, engineering graduate students, and resident surgeons in training. We aim to develop an improved 3D computer model to identify and test optimal approaches for endoscopic access and excision of skull base lesions. Using individualized imaging information, it will offer preoperative surgical rehearsal to improve surgical outcomes and minimize adverse effects. Initially, clinically relevant skull base targets around the pituitar will be defined as locations where tumor invasion often occurs. Virtual endoscopy will be performed to access the specified skull base targets through a variety of endoscopic approaches, including existing standard endoscopic approaches and novel multiportal approaches. The multiportal approach provides wider angles between instruments, which will accommodate current surgical robotic platforms. The model will be validated in cadaver specimens and robotic feasibility will be assessed on two robotic surgery systems. We will use this model to test the hypothesis that multiportal approaches significantly broaden the angle of access to the target and minimize the probability of instrument collisions on set protocols of dissection. It is anticipated that the computer model will demonstrate the shortest, most direct, and least traumatic pathways to skull base targets. Normative data on the approach combinations will be generated and ultimately, these results will serve as a platform for future robotic integration and computer simulation into skull base surgery.